1. Field
Aspects of the present invention relate generally to a multi-mode radar system, and more particularly to an analog-to-digital converter circuit for a radar system that is reconfigurable to operate in a multi-channel, narrow/medium bandwidth mode or a single-channel, wide bandwidth mode, and method of operating the same.
2. Description of Related Art
Radars generally operate in a narrow to-medium instantaneous bandwidth mode for search and track operations by using waveforms that may be sampled with lower-cost, higher fidelity and higher-bit-resolution, narrow/medium band analog-to-digital converters (ADCs). However, high instantaneous bandwidth capability is often used in radars for wideband tracking, threat discrimination, and clutter mitigation, for example. Accordingly, a radar apparatus capable of operating in both narrow/medium band and wide band with similar performance specifications, at both bandwidths, in terms of number of bits of resolution and signal fidelity, is desired.
Ultra-wideband ADCs may meet overall sampling requirements (i.e., capable of narrow to medium or wide band sampling), but generally compromise on dynamic range, spurious-free dynamic range (SFDR), and signal-to-noise ratio (SNR), and have high power consumption, processing, and cost requirements compared to lower bandwidth ADCs.
Alternatively, physically separate narrow/medium band and wideband channels configured in parallel may provide the desired sampling requirements and measurement fidelity for each mode, but providing these separate channels comes at higher cost, lower wideband signal fidelity, and greater real estate, and does not aid in reducing size, weight, and power (SWaP) of the system, which is also desirable.
Stretch Processing and Frequency Jump Burst methods may also provide some wideband capability while using lower-cost narrow/medium band ADCs, but these methods have well-known shortcomings. For example, Stretch Processing must trade-off range extent to achieve the high bandwidth imaging, and Frequency Jump Burst gives up waveform flexibility.
The challenges of the existing wideband or multi-mode radar technology motivate developing an architecture that reconfigurably supports both wideband and narrowband radar functions, in order to mitigate cost and component redundancies, and ideally mitigate fidelity degradation typical of stand-alone ultrawideband ADCs.